Personally I hate wordpress as it consumes tons of resources, We have a client on us doing exactly what your host is saying to you, Eventually we had to put a cap on there domain as it was affecting others.

You cannot do anything on your end but you should ask your host to give you the php name of the file causing the load, If they just say /index.php then you know its wordpress in general.

RSS plugins for wordpress aree nightmares as it drags all the resources to complete but yes, Email them and ask for the exact location of the file causing the load.